Kragg's spindash is by far one of the most punishable moves in Rivals. Most high level Kragg's have put the move to rest and only use it if on tilt or are for sure it will work. It's the second easiest move to parry in the game, second to zetter's fireball. Canceling it yourself is practically putting yourself in the parried state, and having it just end is the same thing.
Actually landing a hit with it gives you the one thing kragg has for combos, nair. Which if above 50 will typically send them really far even with poor DI. (Tested against Etalus, even if i'm moving max speed during cancel I found that Etalus will be able to input an action after the nair before I get to him to combo into something else)
Best grounded scenario is a wavedash cancel into Utilt nair but otherwise it'll just be nair. Kragg has barely any hard to get out of combos, unlike characters like Maypul, Etalus, Zetter, and Forsburn. Kragg isn't a combo character to begin with anyways.(unless you count grounded?) Due to the slow startup of the move it's not like you can use it to 'block' a smash attack. Usually you just get smashed while already in it because the other player felt the need to.
Overall the move punishes itself, since you're giving up almost all control for something nearly useless. A rolling Kragg is one of the best scenarios for most characters. Zetter can get free fire DOT, Orcane can bubble it up, Maypul can seed/plant, Etalus can freeze him and then do some 30+ damage combos. His super armored state is still vulnerable and there is no way to punish anyone with the audacity to attack your current state. Allowing jump canceling at all times will give kragg some much needed mobility and punish game. His recoveries, both pillar and spindash are some of the worst in the game, which kragg just doesn't have what it takes to justify it. Kragg players need to work harder than many at mid to high level play, as that is where kragg starts to show how much his advantage is based on not knowing the mechanics of the game.

I'll admit it's a great move when you're starting out against new players, but after about 6 hours of playing the game with my cousin. His first time, he managed to find it super easy to punish no matter how I used it. Recovery, offense, defense. It's a pretty terrible move. Many players are putting Kragg lower and lower on tiers now, his many nerfs and weaknesses are becoming more clear to the average player, even those who initially complained about how 'OP' he never was.(glitches not included). Super armor has always been something in fighters that sounds OP or amazing on paper, but in the end super armor based characters tend to get sent to the lowest of low tiers. Hugo in SF3:3S/USF4, Hulk in Marvel, Bowser in sm4sh. Hugo is placed 3rd 2nd worst character in street fighter, he has super armor on most specials. Hulk has super armor on nearly everything, considered really low tier. Bowser in sm4sh has super armor on everything, 6th worst character in Sm4sh. I'm having a hard time thinking of moves in fighters with superarmor that aren't terrible outside of SF4's focus attack, which was cancelable. An attack that was easy to avoid by jumping, dashing, or blocking, but could also be canceled at anytime by dashing out of it. Mostly used as a combo extender or parry due to how easy to avoid and punishable it was, much like Kragg's spindash. DP > FADC > Ultra was a bread and butter combo for Ryu. Shoryuken could be canceled into Focus Attack, which could then be canceled by dashing, and then you Ultra. Now if you could only cancel the FocusAttack into a dash on hit but it didn't combo into anything but standing light kick, it'd have never been used. Now to be fair Focus only armored 1 hit, but they also had Red Focus which would go through as many as it wants. You still took 'damage' but it recovered if you didn't get hit for a while. Kragg just soaks up the damage still and can still be knocked back slightly and can't do anything about anyone that does that.

Now let's look at Etalus, he can jump out of a dash attack, dash attack is quick and hard to parry, he can then combo into many different setups, many which involve even more dash attack cancels. He can stock up a large amount of damage in hard to escape combos off of a move that is hard to punish, unless he doesn't cancel. Etalus may not have the super armor, but in a game without a proper blocking mechanic it's hard to avoid his combo setups that start off of an amazing poke.